Timed impact tester



1968 R. H. MARVIN TIMED IMPACT TESTER Filed Aug. 11, 1966 AB C D TIMESECONDS RINVENTOR RICHARD H. MARVIN AGENT Unied isms Paten 3,408,852TIMEDIMPACT TESTER Richard HLMarvin, Philadelphia, Pa., assiguor to TheBudd v .l l l nlmlly,-.Philadelphia, Pa.,'a corporation of. Pennsylvania1 v g FiledAug.1I,1966, Ser. No. 571,91 T7,,Claims. (Cl. 73-12 A iABSTRACT OF THE DISCLOSURE Apparatus for delivering a' series of impactsof con trolled impulse at accurate time intervals. 'A stationary pistonat' one end "of "a cylinder engages ,the body, to be impacted. Arnovable piston is secured to the stationary pistonthrough. a tensionrod having a notched insert. Fluid betweenthe pistons is raised tosuflicient pressure to produce the, impact forceThe tension rodcarriesthis force-andthe fluid is compressed. Explosive imeanswrappedabout'thenotched tension rod may be detonated to rupturethe IbdlThe time to actuate an adjacent like apparatusniay be controlled by thelength of the connecting fuse. v 4 7 This-invention-relates to improvedimpact apparatus andrmore. -particularly, to such apparatus adapted tode liver a series of impacts time'intervalsa,

One environment in which the apparatus of the present inventionfind'suse is in the application of a whipping test for ;seagoing1vessels..The-typical'whipping test isan interpretatiori of--wave. sl-ap-on=.the.forward keelof ahull i from forces producing an essentiallyrunning load which diminishesrtin a forward direction: It is desiredthat the running load ;to-which-the ship is subjected be simulatedbyia-number {of equally. spaced impulsive forces consecu= tively atpredetermined-short intervals, and lasting for a predetermined timeduration. Various typesv of devices includingv rocketmotor .and'gun'type devices in which burning propellants generate animpulsive forcewere previously considered for use in solving this-problem but ity ofenergy storage cells;

I through one of energy cells 3,408,852 Pa en Y t% to the followingdescription taken in connection with'j-th'e accompanying drawing and itsscope will be pointed out in the appended claims. i g I i In the drawingFIG. 1.is a' schematicrepresentation of a test body which is subjectedtoaserie'sfofimpactsv apparatus of the present invention consisting of.ap ale FIG. 2 is a front elevational view of the'tes'tibfody shown inFIG. 1 and'showing lateral suppor'ts'fon each sideofthebody'; l

FIG. 3 is a .vertical sectional view partially schematic, 'oftheapparlatus and showing the same connected in' series to otherlikeunits; 7 FIG. 4' shows a force-timegraph representing an' illtrative application of peaking'forces' ofithe e'nergy'stbrage units tothe test body over a given time relationship.

. Referring toFI G. 1 of the drawing,.thef is' shown test body 10, whichmay be in the form of 'a,-seago'ing vessel, supported on a test bed.'1'1, at load bearing supports 12, 13 along the length of its keel 14.The forwa'i'd portion 15 of the vessel and' its keel 'extend incantilever relation to fixed support 13. A plurality of energy cells,

of controlled impulsefat.accurate were g-rejected as unsatisfactory inthat none have been of controlled impulsive forces during predeterminedtime intervals; It is afurther object of this invention to provide animproved impact apparatus for storing a plurality 'of impulsivev forces-'which maybe triggered consecutively for immediate utilization andwithin an overall allowable time. 1

In accordance with theinvention the impact apparatus is positioned toapply an impulsive force against the test body and comprises energycontainer means havin movable means secured against relative movement byconnecting means. A'fluid "medium .is supplied to the containermeans'with means for regulating its pressure. The connecting meansresists the pressure and cooperates under stress to compress the fluidmedium. Explosive charge means are suitably wrapped around theconnecting means. Upon detonation the connecting means are ruptured andan impulsive force is applied by the apparatus to the test body.

For a better understanding of the present invention together with otherand further objects, reference is had A, B, C, D, are interposed betweenthe cantilevered portion of the keel and the test bed 11, and suitablyarranged to apply forces simulating an essentially running load due towave slap when travelling in a forward direction. As seen in FIG. 2 thevessel is shown supported in a vertical position by means of sidesupports 17, 18 disposed on opposite sides of the body and above theenergy cells applied tothekeel14. '1 In the present instance each of theenergy storage devices A, B, C, D, may be identical and for purposes .ofsimplicity only energy storage cell A is illustrated in detail. As seenin FIG. 3 energy device A is positioned inplace between keel 15 of thetest body 10 and the t'estbedill. It comprises container means 20 whichincludes a cylinder 21 and a stationary piston 23 received withinitsUpper end. The top surface 24 of the piston extends beyond the topedges of the walls of the cylinder and is securedto a high response fiatload cell 25. the load cell is, in. turn secured to a fitting 26 whichis bolted by bolts 27. to the. keel 15 of the test body. The load cell25 is .of convene: tional construction and is used to measure the.,.forces transmitted to the vessel. A movable piston 30 is p n; tionedwithin the bottom open end of the cylinder audit includes shoulderportions 31 which extend laterally or the cylinder and beneath thebottom edges of the cylinder. The latter piston includes an axiallyaligned aperture' 33 which opens from its top surface 34 and joins aslightly enlarged bore 35 which in turn extends to the. bottom snr, face36 of the movable piston. A plurality of shock'ab sorbers 37 carried bya yokemember 38, resting on. test bed 11, engage the under surface 36 ofthe movable piston. Connecting means comprising an axially aligned rod.41, and receiver means in the form of a rupture bolt 44 secure themovable piston 30 against movement. Axial rod 41 extends from the bottomsurface 42 of stationary: piston 23 and passes through theaforementioned aperture 33 in the movable piston and into the bore 35.The lower, end of the rod includes an internally threaded portion 43which receives the threaded shaft portion 45 of theten sion rupture bolt44. The bolt includes a head 47 of greater diameter than the bore 35 andengages the bottom surface 36 of the movable piston. The bolt 44moreover includes an undercut portion 49 along the length of its shaftwhich is in line with transverse apertures 50,;51 passing through thelower portion of the movable piston 30 and opening into theaforementioned vertical'bore 35.

A suitable supply of a fluid medium 55 under pressure such as hydraulicfluid F may be introduced into the cylinder 21 through aperture 56within its sidewall by conduit means 57. The latter is shown asincluding a pressure between upper stationary pistonzs and lower piston30 may be raised to a sufficient level to produce the maximum impactforce applied through the load cell .25 and fitting Z6 onthe keel 15.Theconnecting means 19 com prising tension rod 41 and rupture bolt,44carries this force .while the hydraulic fluid is compressed within thecylinder, Sintiethe" rupture bolt 44is reduced in crosssection as at 49,upon increase in pressure within the cylinder'the bolt becomes loadedunder tension practically to its ultimate tensile strength. IA lengthofcxp'losive charge material 61 is wrapped around the receivermeans atthe notched portion of the tensilerupture bolt 44..One end of. thelength 61 extends within' 'the transverse aperture '50of the movablepiston and'the' other end is received in the oppositely locatedhore..51. A length offuse material L is shown connected to the explosivecharge material 61 within bore 50 and the fus e L may be initiated by anelectric initiator as at 63. When thefuse L and explosive chargeol aredeto nated the notched rupture'rod 44 is ruptured by'virtue of itshighYinitial stress and the shock of detonation. The load o'nthe keelwill initially be the peak impact force.

The force will reduce as the movable piston 30 allows the hydraulicfluid F to expand. As seen in FIG. 4 the force time relationshipdesignated by curve a is essentially triangular. The peak force isdependent upon the maximum fluid pressure. The duration of the appliedforce isdependent upon the yolume and compressibility of the fiuid. Fand the mass of the stationary piston 23 and cylinder wall 21. i

A series of impact testors A, B, C, D, of the above description may belinked according to this invention with lengths Lb, Lo, and Ld ofdetonating fuse material to produce a series of forces and impulses ofcontrolled magnitude at precise sequential time increments. The impulsesso generated could thereby simulate a running load to'which a seagoingvessel is subjected. By assigning a line pressure, for example, of 5,000lbs/in. to the storage cy1- inder A and using pressure regulators 58b,58c, 58d, to respectively supply 4000, 3000, and 2000 lb./in. to theother cylinder (B, C, D) shown connected schematically series tocylinder A, substantially identical energy storage cylinders may beused. When so supplied with pressure the rupture bolts 44b, 44c, and 44dof the energy cells would be undercut in their respective notchedportions 49b, 49c, 490! so that each would be stressed in tension anamount approaching the threshold of its ulti- .dma i aimmt einrentiqnaudit, med in the P- pende'd claims to "eover all "siren" cherries andmesmertions as fall within the true spirit of the scope of theinvention.

What is claimed is:

1. An impact apparatus for a test "body, comprising in combination,energy *storage containerf meahs secured-to saidbody,movable'meanscooperating w storage container-,means to contain afiuid in, means'connecting said-movable piaris'to said container means, means forsupplying a fiuid medium under pressure to saidcontainerniEansYeXplosive charge means, said connecting means; haying,;receive r rne ap s for said explosive charge v means, and means forinitiating said explosivemea'ns to rupture said connecting -means,"whereby said fluid medium expands and'generates ari'impulsive forcewhich istran'sniittedby said containsito saidte's't 2. In: the'ir'np'actapparatus as" set forth'in claim 1 wherein said movable meanscooperating withsaiden'ergy storage container nieanscdnstitiits a pi st3. 1m the "impact apparatus as set forth in' claim 2 wherein said meansconne cting" saidmovable means to said energy storage'cor'itainer meansincludes tension rdd means passingth'rough-said piston.

4. In the impact apparagus as set forth in claim '3 wherein said tension'rod means" comprises a rod extending from said energy storagecontainercmeans and partially through one end vof 'said piston and-abolt including a notched'portion' entering andbottoming on the other endof said piston and threadedly connected to said rod. t r

.5. .Inthe impact apparatusas set forth in claim .4

' wherein said explosive charge means associated. with said means eachsecured tosaid body and comprising movable mate tensile strength. Theabove pressures when applied i to the respective cylinders would produceimpulsive forces of a magnitude of 100,000; 80,000; 60,000; and 40,000lbs./ sec. as seen in FIG. 4.

It is observed that "the length of fuse material Lb interconnectsexplosive charge 61 wrapped around bolt 44 to explosive charge 61bwrapped around bolt 44b. In a similar manner length Lc interconnects theother end of explosivecharge 61b to one end of explosive charge 610wrapped around bolt 44c. Thereafter length Ld is connected to theopposite end of explosive charge 610 and connects the same to charge 61dencircling rupture bolt 44d. In each case the explosive charge materialencircles the bolts at their necked down portions of reduced crosssection. The time required to actuate the successive energy cells A, B,C, and D, is accurately controlled by each of the lengths, L, Lb, L0,and Ld, since the detonation rate is directly proportional to its lengthand is obtainable through calibration. i

While the"re has been described what at present is considered to be thepreferred embodiment of this invention, it will be obvious to thoseskilled in the art that various changes and modifications may be madetherein without meahscooperating-with said container means to'contairi afluid medium therein, means connecting said movable means to each saidcontainer means, means for supplying a fiuid medium-under pressure toeach said container means, explosive charge means, said connecting meanshaving receiver means for said explosive charge means, and meanslinking'the' explosive chargemeans of each said energy storage containermeans in series to detonate the same at precise sequential timeincrementsto rupture said connecting means, whereby said fluid medium ineach of said energy storage container means expands and gen crates animpulsive. force which is transmitted by said container means to saidtest body. 2

7. In the impact apparatus as set forth in claim 6 wherein. theconnecting means of each said energy storage means includes a rupturebolt having a shank portionreduced in cross section an 'amount such thatwhen said .fluid medium under pressure is supplied to said cylindermeans a the same causes said rupture bolt to be loadedin tension anamount approaching the ultimate-tensile strength of the rupture bolt. 'J

References Cited 0

